Belt sanding machine



p 1953 s. JOHANNSEN ETAL BELT SANDING MACHINE Filed March 27, 1951 Patented Sept. 15, 1953 BELT SANDING MACHINE Solvej J ohannsen and Hans Christian J ohannsen, Battenberg (Eder), Germany Application March 27, 1951, Serial No. 217,694

7 In Germany April 3, 1950 3 Claims.

This invention relates to belt abrading n1a chines or belt sanding machines of the kind used for smoothing wood and similar operations and having endless travelling belts each with one surface coated with abrasive material, for example grains of sharp sand or glass powder.

There are known machines in which two belts travel side by side, being driven from a common shaft in the same direction. With such machines it is always the practice to operate with one belt whilst the other runs idly. It is not possible to operate with both belts at once because the sideways force is too great and the operator cannot resist it and exercise adequate sanding pressure. It has therefore been proposed to drive the belts in opposite directions.

One object of the present invention is to provide an improved machine.

According to the invention a belt abrading or belt sanding machine with two belts arranged side by side and travelling in opposite directions is provided with means controlled by a single handle for causing the belts to press against a work-piece and for varying and regulating at will the pressure exerted by each of the belts.

Because the belts travel in opposite directions the side-ways forces on the work-piece are largely or wholly neutralised and thus the operator is relieved of much work and consequent tiredness and can concentrate upon the progress of the operation. Only one operator is necessary at each machine, and his work and efficiency is greatly improved.

In the accompanying drawing the invention is illustrated by way of example,

Fig. 1 being a front elevation of the arrangement of the belts and pressure-regulating device,

Fig. 2. a plan view corresponding to Fig. l, and

Fig. 3, a, side elevation, partly in section, of the pressure-regulating device.

Referring to the drawing, a belt sanding machine comprises a conventionally driven shaft 1 on which are a fast pulley 2 and a loose pulley 3 around which run sanding belts 4 and 5 supported at the upper end of the machine by a loose pulley 6 and a fast pulley l, the latter driven by a drive pulley 8 which receives motion through a V-belt it running on a motor pulley and shaft 9 so that the belts Li and 5 travel in opposite directions.

The pulleys 6 and i run on shafts l2 and H which are arranged in conventional tensioning devices it and It by means of which the correct tensioning and true running of the belts 4 and 5 can be ensured. On a shaft is arranged a slide I6 to which are secured rods H and i8 55 interconnected by a cross-piece I9 to form a bracket-carrying a two-armed swinging member comprising two diverging arms 20 and 2| each having at its lower end an adjustably and pivot== ally mounted presser shoe 22 or 23. Through an aperture in the cross-piece l9 extends a handle rod 24 which is rotatively guided in a tube 25 secured to the slide [6. Two cams 2t and 2'8 are fixed to the rod 24, which carries at its outer end a round knob 28. When the knob 28 is pressed downwards the twin presser shoes 22 and 23, in consequence of their pivotal arrangement and the swinging arrangement of the arms 2| and 20, press downwards with equal pressure against the belts. If the knob 28 be rotated, however, either the arm 20 or the arm 2| is pressed down by the cam 21 or the cam 26 and thus the pressure exerted by one shoe is increased whilst that exerted by the other shoe is decreased. With this changing exertion of the pressure it is ensured that the operator can quickly change from using both belts with pressures as desired to using either belt alone, first one and then the other. This is of particular importance when one of the belts is furnished with coarser abrasive grains than the other.

Various modifications may be introduced without departing from the invention as claimed below, for example the belts with their pulleys can be arranged upon separate shafts such as the shafts of two electric motors of which one drives each belt. The handle rod 24 may be telescopic, which is often advantageous with unusually wide work tables.

We claim:

1. A belt sanding machine of the kind having two sanding belts arranged side by side and travelling in opposite directions, comprising a rocking bracket, 2. two-armed swinging member mounted on said rocking bracket and extending above the lower flights of said belts, two presser shoes pivotally mounted one at each end of said two-armed swinging member and one above each of said belts, a single handle rod rotatably mounted in said rocking bracket, and elements extending laterally from said handle rod and capable of engaging said two-armed swinging member, the arrangement being such that by swinging said handle rod up and down said rocking bracket is rocked and thereby said two-armed swinging member is bodily raised and lowered and by rotating said handle rod said elements engage said two-armed swinging member and thereby the latter is caused to swing and thereby alter vertically the relative positions of said presser shoes one to the other.

2. In a belt sanding machine, the combination of two belts arranged side by side and travelling in opposite directions, a shaft above and substantially parallel to the lower flights of said belts, a bracket mounted on said shaft to be rockable on and axially movable along said shaft, a handle rod rotatably mounted in said bracket, a two-armed swinging member pivotally connected to said bracket, two presser shoes adjustably and pivotally mounted one at each end of said twoarrned swinging member, one of said presser shoes being above the lower flight of one of said belts and the other of said presser shoes being above the lower flight of the other of said belts, and projections on said handle rod capable of engaging said two-armed swinging member, the arrangement being such that by raising and loweringthe' end of said handle rod said bracket is rocked on said shaft and thereby the axis about which said two-armed swinging member swings is raised and lowered and said presser shoes are raised and lowered together, by rotating said. handle rod said two-armed swinging member is engaged by one of said projections and caused to swing and thereby alter in the vertical direction the relative positions of said presser shoes one to the other, and by sideways pressure on said handle rod said bracket is caused to move axially along said shaft thereby moving said presser shoes sideways.

3. A belt sanding machine comprising two belts driven in opposite directions side by side, a shaft above and substantially parallel to the lower flights of said belts, a bracket rotatably and axially slidably mounted on said shaft, a handle rod rotatably mounted in said bracket and extending substantially perpendicularly to said shaft, a two-armed swinging member pivotally attached to said bracket, two presser shoes adjustably and pivotally secured one at each end of said two-armed swinging member, said two presser shoes being one above the lower flight of one of said belts and the other above the lower flight of the other of said belts, and two cams secured to and extending on opposite sides of said handle rod adjacent to said two-armed swinging member, one of said cams being capable of engaging one arm of said two-armed swinging member on rotation of said handle rod in one direction and the other of said cams being capable of engaging the other arm of said twoarmed swinging member on rotation of said handle rod in the other direction.

SOLVEJ JOHANNSEN. HANS CHRISTIAN J OHANNSEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 572,812 Longden Dec. 8,1896 650,004 Brinkman May 22, 1900 7S9,442 Borman Sept. 12, 1905 808,180 Tyden Dec. 26, 1905 818,518 Clemons Apr. 24, 1906 830,116 Tyden Sept. 4, 1906 

